# Lux & Reactant on Colab TPUs

**URL:** <https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926>\
**Category:** Machine Learning\
**Tags:** lux, colab, reactant\
**Created:** [March 13, 2025, 5:06pm UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926 "2025-03-13T17:06:04Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![avikpal](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/avikpal/32/6550_2.png) [@avikpal](https://discourse.julialang.org/u/avikpal)\
**Post date:** [March 13, 2025, 5:06pm UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/1 "2025-03-13T17:06:04Z")

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Colab now has Lux and Reactant pre-installed. Here’s a starter script for TPUs (change the runtime, and it will automatically work on CPU or GPU)

> **[Google Colab](https://colab.research.google.com/drive/13g0PNOJk-x9mbRsRy34tBxSCS0utOPDf?usp=sharing)**

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**Author:** ![finmod](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/finmod/32/26597_2.png) [@finmod](https://discourse.julialang.org/u/finmod)\
**Post date:** [March 14, 2025, 10:08am UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/2 "2025-03-14T10:08:09Z")

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👍Great! “using Optimisers” is missing at the top but otherwise superb

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**Author:** ![brownlight](https://avatars.discourse-cdn.com/v4/letter/b/9d8465/32.png) [@brownlight](https://discourse.julialang.org/u/brownlight)\
**Post date:** [March 16, 2025, 10:14pm UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/3 "2025-03-16T22:14:18Z")

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A positive sign for the increased adoption of Julia in ML.

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**Author:** ![Emrick\_Liu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/emrick_liu/32/30820_2.png) [@Emrick\_Liu](https://discourse.julialang.org/u/Emrick_Liu)\
**Post date:** [January 19, 2026, 2:30am UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/4 "2026-01-19T02:30:25Z")

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This doesn’t seem to work in gpu anymore?  
I’m running on T4, `Reactant.set_default_backend("gpu")` returns: `No GPU client found`

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**Author:** ![giordano](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/giordano/32/2166_2.png) [@giordano](https://discourse.julialang.org/u/giordano)\
**Post date:** [January 19, 2026, 8:52am UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/5 "2026-01-19T08:52:57Z")

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See [Issues with Reactant unable to find GPU on Colab, but CUDA.jl can - #2 by giordano](https://discourse.julialang.org/t/issues-with-reactant-unable-to-find-gpu-on-colab-but-cuda-jl-can/129360/2) and messages below.

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**Author:** ![wsmoses](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/wsmoses/32/26497_2.png) [@wsmoses](https://discourse.julialang.org/u/wsmoses)\
**Post date:** [May 21, 2026, 5:30pm UTC](https://discourse.julialang.org/t/lux-reactant-on-colab-tpus/126926/6 "2026-05-21T17:30:22Z")

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This issue is now fixed upstream in colab in the next release. Using Reactant on the GPU backend will find the devices without further setup